This invention relates to environmental test systems, and more particularly to memory module burn-in testers.
High-availability and critical systems such as web or transaction servers required the use of enhanced-reliability components. Additional testing can be performed on components such as board assemblies, semiconductor chips, and memory modules. Often this additional testing is often performed at an elevated temperature. Thus environmental testing is sometimes known as burn-in.
Weak components often fail earlier at elevated temperatures that at normal temperatures. Poor solder connections on boards or modules can break at higher temperatures, and thermal expansion can loosen poorly seated components. Other manufacturing defects that do not cause immediate failures can create failures that appear after many hours of normal operation at normal temperatures, or after just a few hours at elevated temperatures. Thus elevated-temperature testing can screen for weak components that might later fail in the field, enhancing reliability.
Electronic systems such as servers and personal computers (PCs) use dynamic-random-access memory (DRAM) memory chips mounted on small, removable memory modules. Older single-inline memory modules (SIMMs) have been replaced with dual-inline memory modules (DIMMs), 184-pin RIMMs (Rambus inline memory modules) and 184-pin DDR (double data rate) DIMMs. New kinds of memory modules continue to be introduced.
The memory-module industry is quite cost sensitive. Testing costs are significant, especially for higher-density modules. Specialized, high-speed electronic test equipment is expensive, and the greater number of memory cells on high-speed memory modules increases the time spent on the tester, increasing test costs.
Burn-in testing can be quite expensive, as each module may have to remain at an elevated temperature in a specialized burn-in tester for many hours or even days. Ideally, the memory module is exercised electronically during the burn-in testing, rather than simply be stored at the high temperature and later tested. Operating the memory module at higher frequencies increases internal heating within the DRAM chips, providing more realistic and thorough testing, increasing reliability.
Exercising the memory modules at higher frequencies is difficult, especially when the modules are within a burn-in oven or heated test chamber. Cables or wires that connect an external test-pattern generator or other test equipment to the memory modules within the oven can be long, severely limiting the frequency of operation.
What is desired is a burn-in test system for testing memory modules at elevated temperatures. An elevated-temperature memory module tester is desired that can exercise the memory modules at high frequencies is desirable. A low cost burn-in tester that can be easily repaired and updated is desirable.